| 摘要 |
PURPOSE:To detect securely mismatching attenuation and the presence or absence of discontinuance by connecting a constant current source to the input terminal of a variable resistance attenuator, by connecting a fixed resistor of prescribed impedance to its output terminal, and by inputting its output to an oscilloscope. CONSTITUTION:On vertical axis V3 of the bright spot on the cathode-ray tube of oscilloscope 7, the input resistance value of variable resistance attenuator 4 is shown. On the horizontal axis of the bright spot on the cathode-ray tube, output voltage Vb of variable resistance attenuator 4 developed across fixed resistor 6 is shown and this indicates attenuation A. Into variable resistance attenuator 4, a continuously variable resistance attenuator is inserted to maximize the attenuation of the attenuator, and consequently output voltage Vb decreases, so that the bright spot will be positioned at point A. Further, as the set position of the attenuator is shifted to the minimum attenuation, the bright spot moves to right and stops at position B of the maximum attenuation, so that a bright line can be drawn on the cathode-ray tube. Thus, mismatching attenuation and the presence or absence of discontinuance of attenuation can be detected easily and securely. |
